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Old 5th September 2012, 18:50   #29  |  Link
Makaveli84
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Join Date: Jun 2012
Posts: 71
Sass, what about applying sharpness filters, slowing down effects, etc?? Does that not enhance the artifacts? What if I'd be making a sports video edit that requires slowing down a certain sequence and/or freezing a certain frame for effect or whatever.. I mean sometimes, one would care about even the smallest artifacts that are not visible at regular playback.
For example, the initial difference I was talking about was initially spotted with a moderate sharpness filter applied in MPC-HC playback on both encodes. With filtering off, I was able to spot the difference in freeze-frame. From then on, I was able to tell the difference at regular playback in that sequence with sole focus on the "artifacts area". That's because my eye was by then trained to catch that difference. But this is the whole point of blind testing. You can train as much as you want.
Again, this is very minor, and I'm sorry if my initial post implied that the difference was major. I only wanted to make the point that it was noticeable, but maybe I should've explained in more details.
Anyways, CRF is more than suitable most of the time, but in some cases, when editing and applying effects on videos, I'd like to achieve the best possible quality, even for single frames.
But even for that, I am unconvinced that 2-pass always yields better quality. I mean all that was posted here points to the fact that since 2-pass supposedly uses CRF for its 2nd pass, then there should not be even single-frame differences. However, CRF proponents always say that there is a slight difference that is not worth the extra time. Well, that should be subjective and up to the individual if it's worth it or not. But more importantly, detmek and Sass seem to be at odds regarding whether the 1% minimal difference affects single frame by frame comparisons or not. detmek says yes, Sass says no. Which is it? If 2nd pass is merely a single CRF pass that is not bit identical to CRF because of the impossible task of hitting an exact CRF or bitrate, then one would not expect this very minimal difference to be visible in frame by frame comparisons.
Finally, as an additional test, would encoding 2-pass first, then reading the obtained CRF form x264 logs and then encoding in CRF with the obtained value, would such a test produce bit-identical streams or at least a frame-by-frame match?

Last edited by Makaveli84; 5th September 2012 at 18:55.
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